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Google to double encryption key lengths for SSL certs by year's end

2048-bit keys will be the norm

Google is about to start the first upgrade to its SSL certification system in recent memory, and will move to 2048-bit encryption keys by the end of 2013. The first tranche of changes is planned for August 1.

The new requirements are laid out in a blog post and a FAQ on the topic. The upgrade, based on the guidelines from National Institute of Standards and Technology (NIST), will also see Google's root certificate for signing all of its SSL certificates getting an upgrade from a 1024-bit key.

"There aren't immediate concerns about these certificates being cracked," a Google spokesman told El Reg, "but updating them now provides much better defense against any future risks."

The upgrade is required because NIST thinks it's technically possible that the standard could be broken pretty soon. The first reported factorization of a 768-bit RSA modulus came in December 2009, when an international team of computer scientists and cryptographers spent two-and-a-half years dedicating themselves to the task.

"A 1024-bit RSA modulus is still about one thousand times harder to factor than a 768-bit one," the researchers reported. "If we are optimistic, it may be possible to factor a 1024-bit RSA modulus within the next decade.

"We can confidently say that if we restrict ourselves to an open community, academic effort as ours and unless something dramatic happens in factoring, we will not be able to factor a 1024-bit RSA modulus within the next five years. After that, all bets are off."

NIST estimates it would take six or seven years for any attempt to have a realistic chance of success at breaking 1,024-bit keys, based on the speed of processor development and improvements in factoring computation.

That said, it's still an estimate, and NIST had wanted to get the changeover done faster, with 2010 picked as the original transition date. But because the 1,024-bit standard was so ubiquitous, the schedule was pushed back until the end of this year.

It's the first time anyone can remember the SSL encryption keys getting changed at Google, and it's a measure of the power and sophistication of computer processors that the update is needed. Barring some breakthrough in quantum computing or coding practice, it should be some years before another upgrade is required. ®

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